We have had a Hewitt floating dock for five years and are very pleased with it. Ours is setup to sit lower in the water than the ones pictured on their website. It's an 8' X 30' dock with a 16' ramp. The truss on ours gets wet with any kind of wave action or people on it and acts like a heat sink. With all aluminum construction and an aluminum deck it is never hot on the feet. The dock is bright underneath it and our kids play around it without any of the fear they have had with wooden docks.
The benefits at our lake of a floating dock that moves out as the shoreline moves are huge. There are also no posts anywhere.
The disadvantage is that it is harder to set up a lift on a floating dock. It can move around more during a storm. (The Hewitt runs a cable through sliders under the dock so how tight the cable is and the direction of the waves affect the movement)

Our lake can change 12' in a year but during the summer it may only drip about 6'. The dock can move out about 25' in that time.
Ours looks similar to the one in picture 4 on the linked page.

Floaters are also a little more expensive, particularly if you want a floating lift with it, and you are more limitted if you want a 'boat house' style of dock. 3 or 4 feeet of fluctuation would be OK with a fixed pier if you have at least 2 1/2 feet of water at the low water mark. The key is if that 3 or 4 feet is typical variance or the true min max where there may be years of 6 or 8 feet of variance where you would probably want a foater. The fixed pier would look like it is on stilts when the water is down and if the lake ever 'floods' your dock can go under water. Our lake has a 1-2 foot typical variance, but during high rains my dock has been under 2 feet of water and there have been droughts where I could barely get my boat off the lift with the fixed pier, but those are rare times.

You will get a strong sense which direction to go by seeing what the dominant dock system is on that body of water.

Thanks guys. Most of the people have regular piers. But it seems like there only at the optimal height for a very short time each year. In the spring there under water, and in the fall, it looks like there on stilts. I'd really like to try out a floater.

One other thing that I didn't mention. We have about 50' of cattails to go through before we can get to the pier. There's an old board walk that the people before us had that goes through it. It's super old and falling apart. We need to replace that too. But because of the way the ice shifts, I don't want to put in the same thing and have it get destroyed too. I was actually thinking about getting a couple extra section of floating pier to go through that.

^^^^ Joe, check with the local dock guys and your future neighbors...ther may be other reasons why everyone else is using fixed docks. I was in a similar situation. My lake had certain restrictions enfoced by the state , no one ever told me about untill I started researching it. My dock builder knew about it...that's it.